JP6001509B2 - Marking method for light transmissive substrate and light transmissive substrate - Google Patents

Description

  The present invention relates to a light-transmitting substrate marking method and a light-transmitting substrate. More specifically, the present invention relates to a marking method and a light transmissive substrate that are characteristic of surface treatment of a light transmissive substrate.

  An SOI (Silicon on Insulator) substrate has been widely used in order to reduce parasitic capacitance and to measure the speeding up and power saving of devices. In addition to SOI, SOQ (Silicon on Quartz) in which the handle substrate (supporting substrate) is made of quartz and SOS (Silicon on Sapphire) made of sapphire have been attracting attention in recent years.

  A marking operation is performed on such a Si substrate by using a laser marker to mark the handle substrate with characters or symbols for manufacturing management. When the handle substrate is a light-transmitting substrate, the marking operation is performed by forming a laser absorption film or a colored film on the substrate surface and removing the film with a laser marker, or changing or changing the color of the film.

  There is also a method of marking by selectively opacifying the inside of the light transmissive substrate by irradiating a YAG laser or other short wavelength laser so as to focus on the inside of the light transmissive substrate. There is (for example, Patent Document 1).

JP-A-4-71792

However, each method has advantages and disadvantages. In the case of a method of forming a laser absorption film or a colored film on the substrate surface, an extra substance is attached to the substrate, which may cause contamination of the substrate.
Also, in the case of a method of selectively opacifying the inside of a light transmissive substrate with a YAG laser or the like, it is difficult to apply this method unless the light transmissive substrate is sufficiently thick. When it is applied, it becomes difficult to appropriately and precisely control the concentration depth of the laser beam. Furthermore, quartz and sapphire transmit the YAG laser, and the Si semiconductor film absorbs the wavelength of the YAG laser. Therefore, when a YAG laser is used for SOQ and SOS, the YAG laser may pass through the handle substrate and damage the semiconductor film.
Because of these problems, it is desirable that marking be performed directly on the light-transmitting substrate surface using a carbon dioxide laser with a long wavelength. However, when marking is performed on the light-transmitting substrate surface with a carbon dioxide gas laser, the processed portion irradiated with the laser is melted and sublimated, so that the edge portion is smooth, the contrast of the mark portion is weak, and the visibility is poor. . Therefore, in order to increase the visibility, it is necessary to increase the depth of the marking and greatly change the shape of the groove portion of the mark. This not only requires strong power or multiple laser irradiations, but also raises the periphery of the groove of the mark, affecting the flatness of the light transmissive substrate.
If the light-transmitting substrate is not flat, the bumps on the surface of the light-transmitting substrate will be affected when adsorbed to the chuck part of the semiconductor manufacturing equipment, causing a shift in the position of the semiconductor film surface and adversely affecting device characteristics. give.
The present invention is intended to solve the problems caused by the marking process of such a light-transmitting substrate, while ensuring the quality such as flatness of the light-transmitting substrate, and the substrate in the semiconductor manufacturing process. It is an object of the present invention to obtain a mark having a high visibility necessary for identification of a mark.

  As a result of various studies to solve the above problems, the present inventor conducted a clouding process on the substrate surface in advance before marking on the light transmissive substrate, and then performed marking with a laser marker. The present inventors have found that a marking substrate having excellent visibility can be obtained without impairing the flatness of the present invention, and the present invention has been completed.

That is, the present invention is a method for marking a light transmissive substrate on which a semiconductor film is formed, the first step of performing a clouding treatment on at least a part of the light transmissive substrate surface, and a cloudy treatment surface by a carbon dioxide gas laser. at least seen containing a second step of marking, to a depth of marking 5 to 20 [mu] m, without generating a raised around the groove of the marking, the light-transmitting substrate, a quartz glass substrate, borosilicate It is a marking method selected from the group consisting of a glass substrate and a sapphire substrate .
Further, the present invention includes at least a portion of the light-transmitting substrate surface are processed to cloudy treated surface, by Ri depth laser beam on the cloudy treated surface is marking the 5 to 20 [mu] m, the groove of said marking The light transmissive substrate is a light transmissive substrate on which a semiconductor film is formed. The light transmissive substrate is selected from the group consisting of a quartz glass substrate, a borosilicate glass substrate, and a sapphire substrate .

  According to the marking method of the present invention, visibility can be ensured while maintaining the flatness of the light-transmitting substrate important in the semiconductor manufacturing process by preventing the protrusion around the marking.

The block diagram of a laser marking apparatus. The photograph which shows the visibility at the time of marking on the cloudy process surface of a transparent substrate. The photograph which shows the visibility at the time of marking on the transparent light-transmitting board | substrate surface. The figure which shows the measurement result of the marking depth of the marking part in Comparative Examples 1-4. The figure which shows the relationship between marking depth and the protruding height around the groove part of marking. The figure which shows the measurement result of the marking depth of the marking part in Example 1,2.

Hereinafter, the marking method of the light-transmitting substrate according to the present invention will be described.
In the present invention, the light-transmitting substrate on which the semiconductor film is formed can be manufactured by bonding the semiconductor film and the light-transmitting substrate.
The semiconductor film is not particularly limited, but is selected from the group consisting of a silicon wafer with an oxide film, a single crystal silicon carbide wafer, a single crystal silicon carbide wafer with an oxide film, a single crystal gallium nitride wafer, and a single crystal gallium nitride wafer with an oxide film. it can.
The light transmissive substrate is preferably selected from the group consisting of a quartz glass substrate, a borosilicate glass substrate, and a sapphire substrate. In the present invention, when a carbon dioxide gas laser having a wavelength of 10.6 μm is used as the laser, the above substrate absorbs the carbon dioxide gas laser without passing through it, so that the surface of the substrate can be marked.

  In the present invention, the clouding treatment is performed in order to form irregularities that cause light scattering on the light-transmitting substrate surface. The specific fogging treatment method is not particularly limited, and examples thereof include a sand blast treatment for roughening the surface state of the light-transmitting substrate by hitting abrasive grains, and a method for forming minute irregularities on the surface with a chemical solution.

The marking method of the present invention is characterized in that clouding treatment is performed on the light-transmitting substrate before marking (first step). When the cloudy surface is irradiated with a laser, the irradiated part melts and sublimates, and the surface irregularities that caused light scattering are eliminated and the surface becomes transparent. Therefore, if marking is performed after the clouding process, a transparent laser marking part without light scattering stands out in the clouded surface where light is scattered, and the visibility is improved.
In addition, although the method of performing the clouding process after marking can be taken, the edge of the mark is recognized because not only the unmarked part but also the grooved part or the edge of the mark is clouded. This makes it difficult to obtain sufficient visibility. Further, when the clouding process is performed by a mechanical scratching method such as sand blasting, the processing force may concentrate on the groove bottom of the mark, and a crack may be generated at the groove bottom. Therefore, in the present invention, the clouding process is performed before marking from the viewpoint of sufficient visibility and prevention of cracks.

  In the present invention, the clouding treatment is performed on at least a part of the light transmissive substrate surface. When the clouding process is required for sensing the substrate, the clouding process is performed on the entire surface of the light transmissive substrate. Further, when the light-transmitting substrate surface needs to be transparent, the clouding process is performed only on the portion to be marked. In the case of performing the partial clouding process, it can be performed by masking the part other than the part to be marked.

  In the present invention, the cloudy surface is marked with a carbon dioxide laser (second step). A YAG laser or other laser with a short wavelength is transmitted through the light-transmitting substrate, which may damage the semiconductor film. For this reason, a carbon dioxide laser having a long wavelength and no possibility of transmitting through the light-transmitting substrate is used. In addition, the irradiation intensity | strength and irradiation time of a carbon dioxide gas laser can be made into arbitrary conditions.

  In the marking method of the present invention, the marking depth is preferably 5 to 20 μm. If the depth of the marking is less than 5 μm, it may be difficult to obtain sufficient visibility depending on the shape of the mark. On the other hand, if it is deeper than 20 μm, depending on the shape of the mark, the periphery of the groove of the mark may be raised, which may affect the flatness of the light-transmitting substrate. If the depth of marking is in the range of 5 to 20 μm, sufficient visibility can be obtained while ensuring the flatness of the light-transmitting substrate regardless of the shape of the mark.

By the above marking method, at least a part of the light-transmitting substrate surface is processed into a cloudy treated surface, and the cloudy treated surface is marked with a laser beam. A conductive substrate can be obtained.
The light transmissive substrate of the present invention preferably has a marking depth of 5 to 20 μm.
The scope of claims at the beginning of the filing of the present application is as follows.
[Claim 1] A method of marking a light-transmitting substrate on which a semiconductor film is formed, the first step of performing a clouding treatment on at least a part of the surface of the light-transmitting substrate, and a cloudy treatment surface by a carbon dioxide gas laser. A marking method comprising at least a second step of marking.
[Claim 2] The marking method according to claim 1, wherein the marking depth is 5 to 20 [mu] m.
[3] The marking method according to [1] or [2], wherein the light-transmitting substrate is selected from the group consisting of a quartz glass substrate, a borosilicate glass substrate, and a sapphire substrate.
[Claim 4] A light transmissive substrate on which at least a part of a light transmissive substrate surface is processed into a cloudy treated surface, and the cloudy treated surface is marked with a laser beam. Substrate.
[5] A light-transmitting substrate on which the semiconductor film according to [4] is formed, wherein the depth of marking is 5 to 20 μm.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited to an Example and a comparative example.

[Example 1]
An insulating substrate (SOQ substrate) in which a single-crystal silicon thin film with a thickness of 200 nm is formed on a light-transmitting substrate made of quartz having a diameter of 150 mm and a thickness of 625 μm is used on the entire surface of the insulating substrate. Clouding was performed by sandblasting using silica powder having an abrasive grain size of about 20 μm. After sandblasting, the silica powder was removed by dilute HF cleaning of the light transmissive substrate surface.
Marking was performed on the insulating substrate subjected to the above-described clouding treatment. Specifically, as shown in FIG. 1, the insulating substrate 1 is fixed by the substrate support pins 5 and the laser beam 7 emitted from the laser marker 6 is vertically irradiated on the light transmissive substrate surface 4 which has been subjected to the clouding process. Then, the laser power and the scanning speed were adjusted so that the marking depth was 8 μm. A shutter 8 is provided so that the laser beam is not irradiated onto the light-transmitting substrate surface 4 in cases other than marking. Numbers were used as marking characters, and the size of the numbers was set to a line width of 0.15 mm, a character height of 1.40 mm, and a character width of 1.55 mm.
As a laser marker, a laser marker LP-431 manufactured by SUNX that emits a carbon dioxide laser (wavelength 10.6 μm) was used, and the marking depth was measured with a surface roughness meter Surfcom 130A manufactured by Tokyo Seimitsu.
In addition, by using a positioning mechanism (not shown) that can determine the position of the light-transmitting substrate with good reproducibility, the light-transmitting substrates in the examples and comparative examples are positioned and marked so that the same portion can be marked. did.

[Example 2]
Marking was performed in the same manner as in Example 1 except that marking was performed by adjusting the laser power and the scanning speed so that the marking depth was 15 μm.

[Comparative Example 1]
Example 1 except that marking is performed on an insulating substrate (SOQ substrate) similar to Example 1 without adjusting the laser power and scanning speed so that the marking depth is 32 μm without performing sandblasting. Marking was performed in the same manner.

[Comparative Example 2]
Marking was performed in the same manner as Comparative Example 1 except that marking was performed by adjusting the laser power and the scanning speed so that the marking depth was 55 μm.

[Comparative Example 3]
Marking was performed in the same manner as in Comparative Example 1 except that marking was performed by adjusting the laser power and the scanning speed so that the marking depth was 80 μm.

[Comparative Example 4]
Marking was performed in the same manner as in Comparative Example 1 except that marking was performed by adjusting the laser power and the scanning speed so that the marking depth was 100 μm.

  Table 1 shows the results of the presence or absence of the clouding treatment, the surface average roughness (Ra), the marking depth, the visibility and the flatness in Examples 1 and 2 and Comparative Examples 1 to 4.

FIG. 2 is a photograph showing the visibility when the cloudy surface of the light transmissive substrate is marked. FIG. 3 is a photograph showing the visibility when marking is performed on the transparent substrate surface without being clouded, and FIG. 3A shows the light of the fluorescent lamp on the marking portion. FIG. 3 (b) shows the visibility when only the natural light is used without applying light to the marking portion.
Examples 1 and 2 showed good visibility as shown in FIG. 2 while maintaining the flatness of the light-transmitting substrate (Table 1).
On the other hand, in Comparative Example 1, since the marking was performed deeply, the periphery of the groove portion of the marking was raised, and the flatness of the light-transmitting substrate was impaired. Furthermore, since the clouding process was not performed and the marking depth was not sufficient to ensure visibility, it was visible not only in the case of natural light but also in the case where fluorescent light was projected on the marking part. It was difficult to do. Moreover, since the comparative examples 2-4 did not perform the cloudy process, although it was difficult to visually recognize only with natural light, favorable visibility was acquired by projecting the light of a fluorescent lamp on a marking part. However, the result of the deep marking was that the flatness of the light-transmitting substrate was impaired.

  FIG. 4 is a diagram showing the result of measuring the marking depth of the marked part in the results of Comparative Examples 1 to 4, and shows the effect of the marking depth on the ridge around the groove portion of the marking. . As shown in FIG. 4A, the marking depth is 32 μm (Comparative Example 1) to 100 μm (Comparative Example 4), and the raised portion B around the groove is enlarged in FIG. 4B. It is. In Comparative Example 4 in which the marking depth is 100 μm, the bulge around the groove is prominent, and in the case of Comparative Examples 1 to 3, the bulge around the groove was observed (FIG. 4B).

FIG. 5 is a graph plotting the height of the protrusion around the groove portion of the marking when marking is performed to a predetermined depth in the results of Comparative Examples 1 to 4. In addition to Comparative Examples 1 to 4, the height of protrusions around the groove portion of the marking when the marking was performed to the predetermined depth on the same insulating substrate as that of Comparative Example 1 that was not subjected to the clouding treatment was also plotted.
From this figure, it was found that when the marking depth was 20 μm or less, no protrusion was generated around the groove of the marking, and flatness could be ensured.

FIG. 6 is a diagram showing the result of measuring the marking depth of the marked part in the results of Examples 1 and 2, and FIG. 6A shows the result of Example 1 with a marking depth of 8 μm, FIG. (B) is the result of Example 2 with a marking depth of 15 μm. Compared with the result of FIG. 4, the fluctuation of the baseline in the vicinity of 0 μm is due to the increase in surface irregularities due to the clouding treatment.
From these figures, there is no fluctuation around the groove part of the marking other than the unevenness of the surface due to the clouding treatment, and there is no bulge around the groove part due to the marking, so the flatness of the light transmissive substrate is good. It could be confirmed.

  ADVANTAGE OF THE INVENTION According to this invention, visibility can be ensured, maintaining the flatness of the transparent substrate important in a semiconductor manufacturing process.

1 Insulating substrate 2 Light transmissive substrate 3 Semiconductor film 4 Light transmissive substrate surface 5 Substrate support pin 6 Laser marker 7 Laser light 8 Shutter

Claims (2)

A method of marking a light transmissive substrate on which a semiconductor film is formed,
A first step of performing a clouding treatment on at least a part of the light transmissive substrate surface;
A second step of marking the cloudy surface with a carbon dioxide laser;
At least look including the a depth 5~20μm of said marking, it said without generating bumps around the groove of the marking, the group the light transmissive substrate, a quartz glass substrate, borosilicate glass substrate, made of a sapphire substrate Marking method selected from . At least a portion of the light-transmitting substrate surface are processed to cloudy treated surface, by Ri depth laser beam on the cloudy treated surface is marking the 5 to 20 [mu] m, to generate a raised peripheral groove of said marking The light transmissive substrate on which a semiconductor film is formed , wherein the light transmissive substrate is selected from the group consisting of a quartz glass substrate, a borosilicate glass substrate, and a sapphire substrate.